Field of the Invention
The present invention relates to a mirror angular-positioning apparatus and a processing apparatus.
Description of the Related Art
A galvano apparatus is used in laser processing apparatuses (machine tools) such as a laser drilling machine, laser trimmer, and laser repairer. The galvano apparatus irradiates a target position with laser light by reflecting it by a mirror attached to the rotating shaft of a motor while controlling the rotational angle of the mirror. To accurately align the laser light irradiation position with the target position, it is necessary to accurately control the rotational angle of the mirror. Therefore, the galvano apparatus includes a detector (for example, a capacitive sensor or an optical or magnetic encoder) for detecting the rotational angle of the mirror. Note that the mirror of the galvano apparatus must be rotated at a high speed because the laser processing apparatus is required to have a high operating speed as well.
Also, in the galvano apparatus, if no dynamic balance is obtained between the motor rotating shaft and mirror or if a force generated by a magnet and coil of the motor contains a component in a direction other than the rotational direction, a vibration mode in which the mirror vibrates in a direction in which the mirror falls toward the motor rotating shaft is excited. To suppress this vibration of the mirror in the falling direction, Japanese Patent Laid-Open No. 61-116632 has proposed a technique of adjusting the dynamic balance to the motor rotating shaft.
In this prior art, however, it is impossible to sufficiently remove the vibration of the mirror in the falling direction when rapidly and accurately positioning the laser irradiation position (that is, the mirror rotational angle). In addition, the detector for detecting the mirror rotational angle in the conventional galvano apparatus cannot detect the vibration of the mirror in the falling direction. Accordingly, an article may be processed with this vibration existing, so a processing error may occur in the article. Especially when continuously positioning a laser in a plurality of irradiation positions, a positioning operation succeeding another positioning operation may be performed before the vibration of the mirror in the falling direction sufficiently attenuates. As a consequence, the waves of the vibrations may superpose each other to generate a large vibration.